What I don't understand is that if a proof-of-stake "consensus" algorithm alone is not sufficient to reach consensus, especially when it comes to those nodes that have just joined the network or been offline for a long time, then how can we call it a consensus algorithm in the first place? And if it is not possible to reach a consensus with a pure PoS, then the whole debate becomes meaningless: it simply cannot compete with PoW due to its inherent drawbacks that cannot be fixed except through relying on some less secure punishment mechanisms or timestamp servers based on, again, PoW algorithms.

The trouble is that current stakeholders aren't incentivized at all to sell their stakes for they would make more money and would have more power by just doing nothing. No rational player will give up their power and ever-increasing amount of money for the sake of short-term yields. You aren't incentivized to make others more powerful by selling them tokens either.